Mitochondrial metabolism in the noncancerous liver determine the occurrence of hepatocellular carcinoma: a prospective study

SND1 Regulates Organic Anion Transporter 2 Protein Expression and Sensitivity of Hepatocellular Carcinoma Cells to 5-Fluorouracil

Hepatocellular carcinoma (HCC) is one of the most malignant tumors in the world. Inadequate efficacy of 5-fluorouracil (5-FU) on HCC could be related to low expression of human organic anion transporter 2 (OAT2). However, the knowledge of downregulation of OAT2 in HCC remains limited. We explored the underlying mechanism focusing on protein expression regulation and attempted to design a strategy to sensitize HCC cells to 5-FU. In this study, we revealed that the 1 bp to 300 bp region of OAT2 mRNA 3' untranslated region (UTR) reduced its protein expression and uptake activity in Li-7 and PLC/PRF/5 cells. Mechanistically, it was demonstrated that staphylococcal nuclease and Tudor domain containing 1 (SND1) bound at the 1 bp to 300 bp region of OAT2 mRNA 3' UTR, leading to a decrease in OAT2 protein expression. Enrichment analysis results indicated reduction of OAT2 might be mediated by translational inhibition. Furthermore, the knockdown of SND1 upregulated OAT2 protein expression and uptake activity. Based on this, decreasing SND1 expression enhanced 5-FU-caused G1/S phase arrest in Li-7 and PLC/PRF/5 cells, resulting in suppression of cell proliferation. Additionally, the knockdown of SND1 augmented the inhibitory effect of 5-FU on PLC/PRF/5 xenograft tumor growth in vivo by increasing OAT2 protein expression and accumulation of 5-FU in the tumor. Collectively, a combination of inhibition of SND1 with 5-FU might be a potential strategy to sensitize HCC cells to 5-FU from the perspective of restoring OAT2 protein level. SIGNIFICANCE STATEMENT: We investigated the regulatory mechanism of OAT2 protein expression in HCC cells and designed a strategy to sensitize them to 5-FU (OAT2 substrate) via restoring OAT2 protein level. It found that SND1, an RNA binding protein, regulated OAT2 protein expression by interacting with OAT2 mRNA 3' UTR 1-300 bp region. Through decreasing SND1, the antitumor effect of 5-FU on HCC was enhanced in vitro and in vivo, indicating that SND1 could be a potential target for sensitizing HCC cells to 5-FU.

Endoplasmic reticulum transporter OAT2 regulates drug metabolism and interaction

Xenobiotic metabolic reactions in the hepatocyte endoplasmic reticulum (ER) including UDP-glucuronosyltransferase and carboxylesterase play central roles in the detoxification of medical agents with small- and medium-sized molecules. Although the catalytic sites of these enzymes exist inside of ER, the molecular mechanism for membrane permeation in the ER remains enigmatic. Here, we investigated that organic anion transporter 2 (OAT2) regulates the detoxification reactions of xenobiotic agents including anti-cancer capecitabine and antiviral zidovudine, via the permeation process across the ER membrane in the liver. Pharmacokinetic studies in patients with colorectal cancer revealed that the half-lives of capecitabine in rs2270860 (1324C > T) variants was 1.4 times higher than that in the C/C variants. Moreover, the hydrolysis of capecitabine to 5'-deoxy-5-fluorocytidine in primary cultured human hepatocytes was reduced by OAT2 inhibitor ketoprofen, whereas capecitabine hydrolysis directly assessed in human liver microsomes were not affected. The immunostaining of OAT2 was merged with ER marker calnexin in human liver periportal zone. These results suggested that OAT2 is involved in distribution of capecitabine into ER. Furthermore, we clarified that OAT2 plays an essential role in drug-drug interactions between zidovudine and valproic acid, leading to the alteration in zidovudine exposure to the body. Our findings contribute to mechanistically understanding medical agent detoxification, shedding light on the ER membrane permeation process as xenobiotic metabolic machinery to improve chemical changes in hydrophilic compounds.

Identification and functional analysis of lactic acid metabolism-related differentially expressed genes in hepatocellular carcinoma

Background: Hepatocellular carcinoma (HCC) is a malignant tumor with high morbidity and mortality rate that seriously threatens human health. We aimed to investigate the expression, prognostic value, and immune cell infiltration of lactic acid metabolism-related genes (LAMRGs) in HCC using bioinformatics. Methods: The HCC database (The Cancer Genome Atlas-Liver Hepatocellular Carcinoma) was downloaded from the Cancer Genome Atlas (TCGA). Differentially expressed genes (DEGs) between normal and tumor groups were identified. The LAMRGs were obtained from literature and GeneCards and MSigDB databases. Lactic acid metabolism-related differentially expressed genes (LAMRDEGs) in HCC were screened from the DEGs and LAMRGs. Functional enrichment analyses of the screened LAMRDEGs were further conducted using Gene Ontology (GO) analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, and Gene Set Enrichment Analysis (GSEA). The genes were used in multivariate Cox regression and least absolute shrinkage and selection operator (LASSO) analyses to construct a prognostic model. Then, a protein-protein interaction network was constructed using STRING and CTD databases. Furthermore, the CIBERSORTx online database was used to assess the relationship between immune cell infiltration and hub genes. Results: Twenty-eight lactic acid metabolism-related differentially expressed genes (LAMRDEGs) were identified. The GO and KEGG analyses showed that the LAMRDEGs were related to the prognosis of HCC. The GSEA indicated that the LAMRDEGs were significantly enriched in tumor related pathways. In the multivariate Cox regression analysis, 14 key genes (E2F1, SERPINE1, GYS2, SPP1, PCK1, CCNB1, CYP2C9, IGFBP3, KDM8, RCAN1, ALPL, FBP1, NQO1, and LCAT) were found to be independent prognostic factors of HCC. Finally, the LASSO and Cox regression analyses showed that six key genes (SERPINE1, SPP1, CCNB1, CYP2C9, NQO1, and LCAT) were associated with HCC prognosis. Moreover, the correlation analyses revealed that the expression of the six key genes were associated with immune infiltrates of HCC. Conclusion: The LAMRDEGs can predict the prognosis and may be associated with immune cells infiltration in patients with HCC. These genes might be the promising biomarkers for the prognosis and treatment of HCC.

Integrative Analysis Identifies Cell-Type-Specific Genes Within Tumor Microenvironment as Prognostic Indicators in Hepatocellular Carcinoma

Background

Hepatocellular carcinoma (HCC) is a leading cause of cancer-related mortality worldwide, but effective early detection and prognostication methods are lacking.

Methods

The Cox regression model was built to stratify the HCC patients. The single-cell RNA sequencing data analysis and gene set enrichment analysis were employed to investigate the biological function of identified markers. PLCB1 gain- or loss-of-function experiments were performed, and obtained HCC samples were analyzed using quantitative real-time PCR and immunohistochemistry assay to validate the biological function of identified markers.

Results

In this study, we developed a model using optimized markers for HCC recurrence prediction. Specifically, we screened out 8 genes through a series of data analyses, and built a multivariable Cox model based on their expression. The risk stratifications using the Eight-Gene Cox (EGC) model were closely associated with the recurrence-free survivals (RFS) in both training and three validation cohorts. We further demonstrated that this risk stratification could serve as an independent predictor in predicting HCC recurrence, and that the EGC model could outperform other models. Moreover, we also investigated the cell-type-specific expression patterns of the eight recurrence-related genes in tumor microenvironment using single-cell RNA sequencing data, and interpreted their functional roles from correlation and gene set enrichment analyses, in vitro and in vivo experiments. Particularly, PLCB1 and SLC22A7 were predominantly expressed in malignant cells, and they were predicted to promote angiogenesis and to help maintain normal metabolism in liver, respectively. In contrast, both FASLG and IL2RB were specifically expressed in T cells, and were highly correlated with T cell marker genes, suggesting that these two genes might assist in maintaining normal function of T cell-mediated immune response in tumor tissues.

Conclusion

In conclusion, the EGC model and eight identified marker genes could not only facilitate the accurate prediction of HCC recurrence, but also improve our understanding of the mechanisms behind HCC recurrence.

A Molecular Hepatocellular Carcinoma Prognostic Score System Precisely Predicts Overall Survival of Hepatocellular Carcinoma Patients

BACKGROUND AND AIMS

With high rates of recurrence post-treatment, hepatocellular carcinoma (HCC) is one of the most common types of cancer worldwide and the major cause of cancer death. To improve the overall survival of HCC patients, identification of a reliable biomarker and precise early diagnosis of HCC remain major unsolved problems.

METHODS

We initially screened data from the Cancer Genome Atlas liver cancer cohort to identify potential prognosis-related genes. Then, a meta-analysis of five international HCC cohorts was implemented to validate such genes. Subsequently, artificial intelligence models (random forest and neural network) were trained to predict prognosis accurately, and a log-rank test was performed for validation. Finally, the correlation between the molecular hepatocellular carcinoma prognostic score (mHPS) and the stromal and immune scoring in HCC were explored.

RESULTS

A comprehensive list of 65 prognosis-related genes was obtained, most of which have been not extensively studied thus far. A universal HCC mHPS system depending on the expression pattern of only 23 genes was established. The mHPS system had general applicability to HCC patients (log-rank p<0.05) in a platform-independent manner (RNA sequencing or microarray). The mHPS was also correlated with the stromal and immune scoring in HCC, reflecting the status of the tumor immune microenvironment.

CONCLUSIONS

Overall, the mHPS is an easy and cost-effective prognosis predicting system, which can disclose previously uncovered heterogeneity among patient subpopulations. The mHPS system can further stratify patients who are at the same clinical stage and should be valuable for precise treatment. Moreover, the prognosis-related genes recognized in this study have potential in targeted and immune therapy.

Upregulation of histone acetylation reverses organic anion transporter 2 repression and enhances 5-fluorouracil sensitivity in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors in the world. The failure of chemotherapy in HCC patients is partly due to inadequate intracellular drug accumulation caused by abnormally expressed drug transporters. Human organic anion transporter 2 (hOAT2), a transporter mainly expressed in liver and kidney, is responsible for uptake of various antineoplastic drugs such as 5-fluorouracil (5-FU). Among 32 pairs of human HCC samples, we preliminarily found that OAT2 was suppressed in HCC tissues compared with matched tumor-adjacent tissues at both mRNA and protein levels, which resulted in 5-FU resistance in HCC. However, the epigenetic regulatory mechanisms of OAT2 downregulation have not been investigated. In this study, we first proved it was histone hypoacetylation rather than DNA hypermethylation that participated in transcriptional repression of OAT2 in two HCC cell lines (BEL-7402 and SMMC-7721). In general, there were two pathways confirmed using tissues and cells: 1) Increased histone deacetylase sirtuin 7 (SIRT7) mediated loss of histone 3 lysine 18 acetylation (H3K18ac) at the promoter of OAT2 and inhibited its transcription. 2) More histone deacetylase 7 (HDAC7) instead of lysine acetyltransferase 8 (KAT8) enrichment at the promoter of OAT2 led to low levels of histone 4 lysine 16 acetylation (H4K16ac). Further, we found that histone deacetylases inhibitor vorinostat (SAHA) could reverse histone hypoacetylation state to activate OAT2 transcription and enhance uptake of classic OAT2 substrate zidovudine. Therefore, we evaluated the effect of combining SAHA and 5-FU and the results demonstrated that SAHA could sensitize HCC cells to 5-FU. Collectively, we proposed such a combination treatment to overcome 5-FU resistance in HCC from the perspective of epigenetically restoring OAT2.

Overview of organic anion transporters and organic anion transporter polypeptides and their roles in the liver

Organic anion transporters (OATs) and organic anion transporter polypeptides (OATPs) are classified within two SLC superfamilies, namely, the SLC22A superfamily and the SLCO superfamily (formerly the SLC21A family), respectively. They are expressed in many tissues, such as the liver and kidney, and mediate the absorption and excretion of many endogenous and exogenous substances, including various drugs. Most are composed of 12 transmembrane polypeptide chains with the C-terminus and the N-terminus located in the cell cytoplasm. OATs and OATPs are abundantly expressed in the liver, where they mainly promote the uptake of various endogenous substrates such as bile acids and various exogenous drugs such as antifibrotic and anticancer drugs. However, differences in the locations of glycosylation sites, phosphorylation sites, and amino acids in the OAT and OATP structures lead to different substrates being transported to the liver, which ultimately results in their different roles in the liver. To date, few articles have addressed these aspects of OAT and OATP structures, and we study further the similarities and differences in their structures, tissue distribution, substrates, and roles in liver diseases.

Investigation of the SLC22A23 gene in laryngeal squamous cell carcinoma

Background

Laryngeal squamous cell carcinoma (LSCC) is the second most common cancer of the head and neck. In order to identify differentially expressed genes which may have a role in LSCC carcinogenesis, we performed GeneFishing Assay. One of the differentially expressed genes was the SLC22A23 (solute carrier family 22, member 23) gene.

SLC22A23 belongs to a family of organic ion transporters that are responsible for the absorption or excretion of many drugs, xenobiotics and endogenous compounds in a variety of tissues. SLC22A23 is expressed in a various tissues but no substrates or functions have been identified for it. Although the exact function is unknown, single nucleotide polymorphisms (SNPs) which are located in SLC22A23 gene were associated with inflammatory bowel disease (IBD), endometriosis-related infertility and the clearance of antipsychotic drugs. On the other hand SLC22A23 is identified as a prognostic gene to predict the recurrence of triple-negative breast cancer.

Methods

To understand the role of the SLC22A23 gene in laryngeal carcinogenesis, we investigated its mRNA expression level in laryngeal tumor tissue and adjacent non-cancerous tissue samples obtained from 83 patients by quantitative real-time PCR. To understand the association between SNPs in SLC22A23 and LSCC, selected genetic variations (rs4959235, rs6923667, rs9503518) were genotyped.

Results

We found that SLC22A23 expression was increased in 46 of 83 tumor tissues (55.4%) and was decreased in 30 of 83 (36.1%) tumor tissues compared to normal tissues. 77.2% of patients were homozygote for genotype rs9503518-AA and they most frequently had histological grade 2 and 3 tumors. We also found that rs9503518-AA genotype is associated with increased SLC22A23 expression.

Conclusions

Our results indicate that SLC22A23 may play a role in the development of laryngeal cancer.

Gene network analysis reveals a novel 22-gene signature of carbon metabolism in hepatocellular carcinoma

Although much progress has been made in understanding cancer cellular metabolism adaptation, the co-regulations between genes of metabolism and cancer pathways and their interactions remain poorly characterized. Here, we applied gene co-expression network analysis to 1509 metabolic gene expression data generated from 120 HCC and 180 non-tumor human liver tissues by microarray. Our analyses reveal that metabolism genes can be classified into different co-expression modules based on their associations with HCC related traits. The co-regulation mechanism of the carbon metabolism genes in normal liver tissues was interrupted during the processes of carcinogenesis. In parallel, we performed RNAseq analysis of HCC and non-tumor human liver tissues, and identified a unique 22-carbon-metabolism-gene-signature of increased expression. This gene signature was further verified in multiple microarray data sets, and its prognostic value was also proven by HCC patients' survival data from TCGA. Additionally, the tumorigenic function of two representative genes, CS and ACSS1, were validated experimentally by cell growth and spheroid formation assays. The current study provides evidence for the reprogramming of the co-regulation network between carbon metabolism and cancer pathway genes in HCC. In addition, this study also reveals a unique 22-carbon-metabolism-gene-expression-signature in HCC. Strategies targeting these genes may represent new therapeutic approaches for HCC treatment.

TMEM88, CCL14 and CLEC3B as prognostic biomarkers for prognosis and palindromia of human hepatocellular carcinoma

Hepatocellular carcinoma is one of the most mortal and prevalent cancers with increasing incidence worldwide. Elucidating genetic driver genes for prognosis and palindromia of hepatocellular carcinoma helps managing clinical decisions for patients. In this study, the high-throughput RNA sequencing data on platform IlluminaHiSeq of hepatocellular carcinoma were downloaded from The Cancer Genome Atlas with 330 primary hepatocellular carcinoma patient samples. Stable key genes with differential expressions were identified with which Kaplan-Meier survival analysis was performed using Cox proportional hazards test in R language. Driver genes influencing the prognosis of this disease were determined using clustering analysis. Functional analysis of driver genes was performed by literature search and Gene Set Enrichment Analysis. Finally, the selected driver genes were verified using external dataset GSE40873. A total of 5781 stable key genes were identified, including 156 genes definitely related to prognoses of hepatocellular carcinoma. Based on the significant key genes, samples were grouped into five clusters which were further integrated into high- and low-risk classes based on clinical features. TMEM88, CCL14, and CLEC3B were selected as driver genes which clustered high-/low-risk patients successfully (generally, p = 0.0005124445). Finally, survival analysis of the high-/low-risk samples from external database illustrated significant difference with p value 0.0198. In conclusion, TMEM88, CCL14, and CLEC3B genes were stable and available in predicting the survival and palindromia time of hepatocellular carcinoma. These genes could function as potential prognostic genes contributing to improve patients' outcomes and survival.

A Global Risk Score (GRS) to Simultaneously Predict Early and Late Tumor Recurrence Risk after Resection of Hepatocellular Carcinoma

OBJECTIVES: Recurrence of hepatocellular carcinoma can arise from the primary tumor (“early recurrence”) or de novo from tumor formation in a cirrhotic environment (“late recurrence”). We aimed to develop one simple gene expression score applicable in both the tumor and the surrounding liver that can predict the recurrence risk. METHODS: We determined differentially expressed genes in a cell model of cancer aggressiveness. These genes were first validated in three large published data sets of hepatocellular carcinoma from which we developed a seven-gene risk score. RESULTS: The gene score was applied on two independent large patient cohorts. In the first cohort, with only tumor data available, it could predict the recurrence risk at 3 years after resection (68 ± 10% vs 35 ± 7%, P = .03). In the second cohort, when applied on the tumor, this gene score predicted early recurrence (62 ± 5% vs 37 ± 4%, P < .001), and when applied on the surrounding liver tissue, the same genes also correlated with late recurrence. Four patient classes with each different time patterns and rates of recurrence could be identified based on combining tumor and liver scores. In a multivariate Cox regression analysis, our gene score remained significantly associated with recurrence, independent from other important cofactors such as disease stage (P = .007). CONCLUSIONS: We developed a Global Risk Score that is able to simultaneously predict the risk of early recurrence when applied on the tumor itself, as well as the risk of late recurrence when applied on the surrounding liver tissue.

Genetic polymorphism of the human organic solute carrier protein 1 (hOSCP1) gene in Japanese patients with non-viral liver carcinoma

Human organic solute carrier protein 1 (hOSCP1) is a Na⁺-independent multispecific organic solute transporter. To date, several studies have revealed that gene mutations of the transporters are likely to be associated with some diseases; however, there are no data concerning the genetic polymorphism of the hOSCP1 gene in Japanese patients with non-viral liver carcinoma (LC). In the present study, we isolated genomic DNA from a normal portion of LC, and analyzed 41 single nucleotide polymorphisms (SNPs) chosen from a database of SNPs (dbSNPs). We found genotype frequencies for 2 non-synonymous SNPs [rs34409118 (Thr¹³¹ → Ala) and rs1416840 (Ile²¹⁹ → Thr)] and 1 synonymous SNP [rs16822954 (Ser¹⁹³ → Ser)] to be statistically significant when compared with dbSNPs. No statistical significance was observed in rs2275477 (Gly³⁰⁷ → Arg) in the hOSCP1 gene. With respect to the allele frequency, we also observed rs34409118 to be statistically significant. Interestingly, we found that non-viral LC patients do not carry heterozygous mutations in rs1416840 (A/G) and rs16822954 (A/G), suggesting that a non-carrier of heterozygous mutations in these two SNPs might be a biomarker for susceptibility for non-viral LC in Japanese. Further analyses of patients with hOSCP1 variants may elucidate the relationship between the hOSCP1 gene and susceptibility of non-viral LC in Japanese patients.

Alcohol consumption and recurrence of non-B or non-C hepatocellular carcinoma after hepatectomy: a propensity score analysis

BACKGROUND

The aim of this study was to identify factors related to the recurrence of non-B or non-C (NBNC) hepatocellular carcinoma (HCC).

STUDY DESIGN

Between April 2000 and March 2012, out of 621 consecutive HCC patients at our institution, 543 who underwent initial hepatectomy and had no extrahepatic metastases were enrolled in the study. Multivariate analysis were performed to identify risk factors for poor disease-free survival (DFS).

RESULTS

The 5-year DFS rate of NBNC (34 %) was better than that of hepatitis virus B (30 %, P = 0.011) and hepatitis virus C (21 %, P < 0.0001), significantly. Multivariate analysis revealed NBNC [hazard ratio (HR), 0.5; 95 % CI, 0.4-0.8; P < 0.0001)] to be an independent factor for DFS rate. We constructed a propensity score matching model with the 543 patients, and the 5-year DFS rates with and without severe alcohol liver disease (ALD) were 31.6 and 47.5 %, respectively (P = 0.013). In the 163 NBNC patients, severe ALD, mild ALD, and no ALD were seen in 35, 56, and 72 patients, respectively. Multivariate analysis revealed a vascular invasion into the hepatic vein (HR, 3.3; 95 % CI, 1.7-6.3; P < 0.0001) and severe ALD (HR, 2.0; 95 % CI, 1.1-3.6; P = 0.020) to be independent risk factors for poor DFS. By propensity score matching between mild and severe ALD, the 5-year DFS rates with severe and mild ALD were 26 and 50 %, respectively (P = 0.035).

CONCLUSIONS

The prognoses of NBNC patients were better than those of patients with viral infections. Among the NBNC patients, preoperative excessive alcohol intake decreased DFS rate of HCC occurrence after surgery.